<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<script>
    for (var k=1;k<=6;k++){
        for (var i=1;i<=k;i++){
            document.write("*");
        }
        document.write("<br>")
    }

</script>
</body>
</html>